Multiple polarization orders in individual twinned colloidal nanocrystals of centrosymmetric HfO2

Du, Hongchu; Ohlerth, Thorsten; Jia, Chun-Lin; Dunin-Borkowski, Rafal E.; Groh, Christoph; Simon, Ulrich; Mayer, Joachim

doi:10.1016/j.matt.2020.12.008

Journal Article

FZJ-2021-01666

Multiple polarization orders in individual twinned colloidal nanocrystals of centrosymmetric HfO2

Du, H. (Corresponding author)FZJ* ; Groh, C. ; Jia, C.-L.FZJ* ; Ohlerth, T. ; Dunin-Borkowski, R. E.FZJ* ; Simon, U. ; Mayer, J.FZJ*

2021
Elsevier [New York, NY]

Matter 4(3), 986 - 1000 (2021) [10.1016/j.matt.2020.12.008]

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Please use a persistent id in citations: http://hdl.handle.net/2128/27539 doi:10.1016/j.matt.2020.12.008

Abstract: Spontaneous polarization is essential for ferroelectric functionality in non-centrosymmetric crystals. High-integration-density ferroelectric devices require the stabilization of polarization in small volumes. Here, atomic-resolution transmission electron microscopy imaging reveals that twinning gives rise to multiple polarization orders without symmetry breaking in colloidal nanocrystals of HfO2. The polarization orders are associated with sub-nanometer ferroelectric and antiferroelectric phases. The minimum size limit of the ferroelectric phase is found to be ∼4 nm3. Density functional theory calculations indicate that transformations between the ferroelectric and antiferroelectric phases are energetically possible. This work provides a route toward applications of HfO2 nanocrystals in information storage at densities that are more than an order of magnitude higher than the scaling limit defined by the nanocrystal size. Our results on the formation of twinning-induced polarization orders without symmetry breaking may provide general guidance for the discovery of new ferroelectric phases in ionic compounds that are not restricted to oxides.

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